Help opening a dialog box for inserting an image

I have a simple solution for my t-shirt printing shop and I'm trying to be able to add an image to a container through a script step. I want to be able to simply locate the image file on my windows machine and have it inserted into the container. So imagine you are in excel and you choose the "open file" command. Windows pops open a dialog window allowing you to find the file you want to open on your machine or network. I want Filemaker to do that as well, but in my case I'll be looking to just insert that image into the container.

I figured this out with your help. Apparently Filemaker has to have the container of the image on the layout that you are executing the script on. So the solution above works, but only if the container that you want the image on is on the form.

This is something that has been with Filemaker since the beginning and I would really like them to change it. There is no reason that I can think of that you should have to have a field visibly present on the screen / form in order to perform a function related to that field. You should be able to drop values into a field without it being on screen.